The present invention relates to a support assembly adapted for rotatably supporting a shaft of a spinning rotor of an open end yarn spinning apparatus.
Conventional open end yarn spinning machines comprise a plurality of side-by-side spinning positions. Each spinning position has a spinning rotor which is rotated at high speed, and which receives the yarn fibers from a fiber feed duct and forms a band of fibers which is subsequently withdrawn as a twisted yarn. The rotor includes a coaxial rotor shaft which extends from the rearward side of the rotor, and the shaft is most commonly supported for rotation by a so-called "twin disc" bearing arrangement composed of two support assemblies mounted in adjacent pairs to form a wedge shaped cusp for rotatably supporting the shaft of the rotor.
Each support assembly of the above described type typically comprises a pair of axially spaced apart discs, which are mounted on a common support shaft, and each support shaft is in turn mounted to the frame of the machine by means of a suitable bearing which is fixed on the support shaft and releasably mounted to the machine frame, so that the support shaft and discs are freely rotatable. Rotation is imparted to the rotor shaft by contact with a drive belt, which advances along the length of the machine, and so that rotation is also imparted to the discs and support shafts of the two support assemblies.
The discs of the support assemblies each comprise a solid metal wheel which is joined to the common support shaft by a press fit, and the outer periphery of the wheel mounts a tire of plastic or other hard rubber-like material, and which directly supports the shaft of the spinning rotor. As will be readily understood, the tires of the discs wear out in time, such as about once a year, and it is present practice to change the tires by initially withdrawing the rotor and then removing each support assembly from the frame of the apparatus. Once each support assembly is removed, the discs with the worn tires are removed from the support shaft at the press fit and discarded, and new discs with new tires are installed on the support shaft by a new press fit. The assembly is thereafter repositioned in the frame of the apparatus.
As will be apparent, the repeated removal and reconnection of the press fit between the wheels of the discs and the support shaft is not only a labor intensive operation, but it can also result in the scoring of the support shaft and wheel bore, which can lead to imbalances, and also to the deterioration and release of the press fit, thereby requiring that the shaft and bearing be discarded before the end of the useful life of the bearing. Also, the fact that the entire disc is discarded with the worn tire results in the loss of the relatively expensive metallic wheel and thus increases the expense of the operation.
It is accordingly an object of the present invention to provide a support assembly for rotatably supporting the shaft of a spinning rotor of an open end yarn spinning apparatus, and which effectively avoids the above noted limitations and disadvantages of the present constructions.
It is a more particular object of the present invention to provide a support assembly of the described type which permits the plastic tires of the discs to be readily changed when the plastic tires become worn, while avoiding the need to remove the wheels of the discs from the support shaft, and so that the press fit on the support shaft is not disturbed.
It is also an object of the present invention to provide a support assembly of the described type which permits the tires to be replaced upon becoming wore, without loss of a significant amount of metallic material, to thereby minimize the expense of the tire replacing operation.